20" wheels on the farm

[BruceWard]

I bought a 2007 GMC truck last week. Unfortunately it has 20" wheels. The manual says not to use the 20" wheels offroad. My previous truck had 265/75R16 Goodyear Wrangler Silentarmor tires. I am considering either trading the 20s for smaller wheels or installing 275/60R20 Silentarmor tires.

Do you think the 275/60R20 tires with 6.5" sidewalls will work ok offroad? I frequently find stump holes with tires or drive on less than 6" rocks.

I appreciate any and all advice.

Thanks.

 

[Opti-Mist]

You should probably have a talk with a GMC dealer. There are design considerations that result in that wheel & tire combo on that vehicle. Make sure that you aren't creating an unintended adverse consequence with your proposed change.

 

[Diamondpilot]

I would be afraid of denting a wheel with the small side wall 20's have. I would also be concerned with breaking the bead.

Not sure what size truck you have but my neighbor bought a Chevy 3500 with 20's and he pulls a 5th wheel camper. Looking at the load capacity of the 20" tires there was not enough load capacity for him. He had to get a set of the factory aluminum wheels, I think in 16's, then put on 285's on it.

Also take a look at the Goodyear Duratrac if you like Goodyears. That is what my neighbor has on his 3500 and they are a nice tire.

http://www.tirerack.com/tires/tires.jsp?tireMake=Goodyear&tireModel=Wrangler+DuraTrac

Chris

 

[BruceWard]

The Silentarmor tires are a little less agressive than DuraTrac.

SilentArmor

Duratrac

The SilentArmor tires have kevlar plys and are rated for higher speed than the Duratrack 119 mph vs 99 mph.

The truck is a 2007 1500. The 2640 pound capacity of the SilentArmor tires is plenty for me.

The truck in this picture has 285/60R20 Duratacks

Looking at it I am thinking that I can live with that amount of sidewall.

 

[dodge man]

I'm not for sure, but I don't think you can get the silentarmours in 20" size. My Dodge came with 20's and I got a set of aftermarket wheels in 18" and got Silentarmours in a taller sidewall that worked out to the same diameter as the 20" tires. Do a google on Tire Rack, they have alot of tires for sale.

 

[brin]

When you change the wheel size does that not throw of the speedometer ?

 

[aczlan]

When you change the wheel size does that not throw of the speedometer ?

You have to change tire size to match the OEM tire diameter. See here to play with tiresizes to keep the tire diameter the same (or close).
For example a 265-65-R20 tire is almost the same size as a 285-70-R18 one (the 18" tire would make the speedometer read 60 MPH when you are going 60.3 MPH) or a 295-75-R16 one

Aaron Z

 

[BruceWard]

I plan to have the ECU reprogrammed to set the speedometer for the size of whatever tire is installed.

Silentarmors are available in 275/55R20 (oem 32"), 275/60R20 (33"), 285/60R20 (33.5") and 305/60R20 (34.4"). The 285s and 305s are way to expensive for me.

But my big issue is whether to stick with the factory 20 inch wheels with a little bigger tires or buy 18" wheels for 275/70R18 (33.2") tires. I am starting to believe the 20s with bigger tires may be ok.

 

[Diamondpilot]

Make sure you rim width is in the range of the tires. I think anything bigger than 285 will give you issues.

Chris

 

[RobertN]

This is personal opinion for years of Jeeps, and 4x4 trucks. Lots of wheelin, plenty of rocks(Rubicon ect).

Get a set of 16" or 17" and a set of 285's or similar with some sidewall to them. If you really use it off road, maybe even steel rims. 20's are a pretty street tire, for some I guess. Off road though? I would tear those rims to shreds out hunting. I can't take my full size long bed xcab truck where I took the Jeeps, but it still gets used.

Make sure of your brake size; a 16" may not clear your rotors.

Also make sure the rim/tire combo is ok for the weight you may carry or tow.

I like the Cepck mud tires I have now(almost ready for a new set. 285's on factory 16" rims. As big as I want to go, especially since the truck already sits high stock; my 5th wheel has the axles flipped so it is taller to fir the truck already...